Allow for sig chain to be disabled.

Tools like dex2oat or patchoat don't need the sig chain or the fault
manager. This also enables building a statically link version of
dex2oat.

Change-Id: I9897728cac48acade854bb027bfde860628ebf84
diff --git a/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index 74d5c0c..b4520e9 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -1129,6 +1129,9 @@
     if (!image_) {
       runtime_options.push_back(std::make_pair("-Xno-dex-file-fallback", nullptr));
     }
+    // Disable libsigchain. We don't don't need it during compilation and it prevents us
+    // from getting a statically linked version of dex2oat (because of dlsym and RTLD_NEXT).
+    runtime_options.push_back(std::make_pair("-Xno-sig-chain", nullptr));
 
     if (!CreateRuntime(runtime_options)) {
       return false;